Dodziuk Helena, Nowinski Krzysztof S, Kozminski Wiktor, Dolgonos Grigory
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland.
Org Biomol Chem. 2003 Feb 7;1(3):581-4. doi: 10.1039/b209272g.
Knowledge of stepwise binding constants for complexes with higher than 1:1 stoichiometry would allow one to study the cooperativity of their formation. However, a detailed analysis of partitioning of the overall binding constant beta 12 determined by NMR titrations for the 1:2 complex of (+)-camphor with alpha-cyclodextrin into the stepwise ones K1 and K2 carried out analogously to published procedures revealed that the partitioning cannot be carried out unequivocally for K1 << K2. The programs for partitioning cannot be used as a black box and a satisfactory reproduction of the experimental dependence of relative shifts as a function of relative CD concentration should not be the only criterion of the reliability of the stepwise binding constants obtained using such programs.
了解化学计量比高于1:1的配合物的逐步结合常数，将有助于研究其形成的协同性。然而，按照已发表的方法，对(+)-樟脑与α-环糊精的1:2配合物通过核磁共振滴定法测定的总结合常数β12，进行逐步常数K1和K2的分配详细分析后发现，对于K1 << K2的情况，分配无法明确进行。分配程序不能作为黑箱使用，并且相对位移随环糊精相对浓度变化的实验依赖性的令人满意的重现，不应是使用此类程序获得的逐步结合常数可靠性的唯一标准。
